It was a cold Saturday. I had my coffee and a plan. I needed to change the tires on my truck. It is a job I have done many times.
I grabbed my Milwaukee M18 Fuel impact wrench. I love this tool. It is strong. It should remove rusted nuts easily.
I jacked up the truck. I put the socket on the first lug nut. I pulled the trigger.
Whirr-CLACK… silence.
The tool stopped. The nut did not move. A light flashed on the handle. I tried again. Nothing. It felt like the battery was dead.
I was worried. Did I break my expensive tool? Was the motor burnt?
If you are reading this, you are likely in your driveway too. You look frustrated. I know that feeling. But do not worry. I learned something that day. When an impact wrench stops, it is rarely broken. It is trying to tell you something.
Here is what I went through. Here is how I fixed it.
The Tool Has a Brain
Old tools were simple. You pulled a trigger. Power flowed until something broke.
New tools are different. They are smart.
My wrench did not stop because it was weak. It stopped because of its computer. Inside the handle, there is a small circuit board. It watches the motor.
I tried to hit a stuck nut. The motor asked for a lot of power. The board saw this spike. It said, “Too much heat! Stop!”
This is called Overload Protection. It feels annoying. But it saves your battery from fire.
The “Auto-Stop” Mistake
This was my first error. I felt silly when I found it.
I looked at the bottom of my wrench. There are buttons to change speed. I usually use “3” for max power.
But the light was on a different icon. It looked like a bolt with an arrow.
This is Auto-Shutoff Mode.
Brands like Milwaukee and Makita have this. It stops the tool the moment it hits. It saves you from breaking bolts. But on a rusty lug nut? It feels the first hit and cuts the power.
The Fix:
I pressed the button. I moved the light back to “High.” I tried the nut again. It ran longer, but it still cut out. So, I had another problem.
The Battery Trick
I looked at my battery light. It showed two bars.
“Two bars is fine,” I thought. “That is half full.”
For a drill? Yes. For a big impact wrench? No.
An impact wrench needs a huge burst of power to start. If the battery is half empty, the voltage drops fast. The tool feels this drop. It thinks the battery is dead. It cuts the power to be safe.
The Fix:
I went to my charger. I grabbed a full battery. I put it on the wrench.
I went back to the tire. CLACK-CLACK-ZZZT. The nut spun off.
Lesson: If your tool acts weird, charge the battery. Always use a full pack for tires.
The Wiggle Problem
Later that day, it happened again. The battery was full. The mode was right. But the tool would stop after one second.
I was mad.
I watched closely. Every time the hammer hit, the tool shook hard.
The battery was wiggling. The metal parts inside lost contact for a split second. This reset the tool’s computer.
The Fix:
I used my other hand. I held the battery tight against the tool. I pulled the trigger. It worked.
If your battery is loose, the shaking will turn the tool off.
If You Use Air Tools
My neighbor saw me working. He walked over. He uses air tools, not battery ones. He told me he has the same issue.
If an air tool stops or slows down, it is usually Air Starvation.
Imagine drinking a thick shake through a tiny straw. You cannot get enough. That is your tool on a small hose.
- The Hose: If you use a thin hose, the tool starves. You need a thick hose (3/8 inch).
- The Tank: If your tank is small, it runs out of air in seconds. The power fades.
Quick Fix Guide
Here is a table to help you fast. I wish I had this on that Saturday.
| What Happens | Why It Happens | The Fix |
| Lights flash, tool stops | Overload Protection | Let go of trigger. Wait. Try again. |
| Hits once then stops | Auto-Stop Mode is on | Change speed to “High” or “3”. |
| Runs for 2 sec then dies | Low Battery Power | Use a 100% charged battery. |
| Cuts out while shaking | Loose Battery | Hold the battery tight with your hand. |
| Motor runs, socket sits still | Broken Part | This is mechanical. You need repairs. |
| (Air) Tool slows down | Not Enough Air | Use a bigger hose. Let tank fill. |
When to Stop
Sometimes, we ask too much of our tools.
There was one nut on the rear wheel. It was rusted solid. My impact wrench hammered on it for 15 seconds. The tool got hot.
If you hold the trigger for 10 seconds and the nut does not move, stop.
You are just making heat. You might melt the wires.
The “Old School” Fix:
I put the power tool down. I grabbed my long breaker bar.
I put it on the nut. I leaned on it. POP. The rust broke.
Once it was loose, I used the impact wrench to spin it off. There is no shame in this. It saves your tool.
Summary
That Saturday taught me a lot. A stopped tool is not always junk.
My checklist for next time:
- Check the Mode: Is it on “Smart” mode? Turn it off.
- Check the Charge: Is it full? If not, swap it.
- Check the Fit: Is the battery loose? Hold it.
- Know the Limit: If it is stuck, use a bar.
Tire changes are hard work. But they are easier when your tools work. I hope this helps you get back on the road.
FAQs – Impact Wrench Stops Suddenly
Why does my impact wrench stop when I pull the trigger?
It may be in “auto mode.” This stops the tool fast. Also, a low battery cuts power. Charge it up and try again.
How do I fix an impact wrench that stops under load?
Use a full battery. Weak ones stop when working hard. Hold the battery tight to the tool. Loose parts can cut the power.
Why does my Milwaukee impact wrench stop after one hit?
It is likely in “Auto Mode.” This mode stops it fast. Switch the dial to High. This gives full power for stuck nuts.
Can a low battery cause my impact wrench to stop?
Yes, it can. These tools need lots of power. If the charge is low, it stops. Swap in a fresh pack.
Do I need a breaker bar if my impact wrench stops?
Yes, for stuck nuts. If the tool fails, stop. Break the nut loose by hand first. This saves your motor.